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The pseudoachromatic index of a graph is the maximum number of colors that can be assigned to its edges, such that each pair of different colors is incident to a common vertex. If for each vertex its incident edges have different color,…

Combinatorics · Mathematics 2018-09-26 O. Aichholzer , G. Araujo-Pardo , N. García-Colín , T. Hackl , D. Lara , C. Rubio-Montiel , J. Urrutia

The distinguishing index of a graph $G$, denoted by $D'(G)$, is the least number of labels in an edge labeling of $G$ not preserved by any non-trivial automorphism. The distinguishing chromatic index $\chi'_D (G)$ of a graph $G$ is the…

Combinatorics · Mathematics 2017-12-12 Saeid Alikhani , Samaneh Soltani

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$ labels that is preserved only by a trivial automorphism. A set $S$ of vertices in $G$…

Combinatorics · Mathematics 2017-07-20 Saeid Alikhani , Samaneh Soltani

Let $G=(V,E)$ be a simple graph. A set $S\subseteq V(G)$ is called an outer-connected dominating set (or ocd-set) of $G$, if $S$ is a dominating set of $G$ and either $S=V(G)$ or $V\backslash S$ is a connected graph. In this paper we…

Combinatorics · Mathematics 2024-02-19 Saeid Alikhani , Mohammad H. Akhbari , C. Eslahchi , Roslan Hasni

Let $G$ be a finite simple connected graph on $[n]$ and $R = K[x_1, \ldots, x_n]$ the polynomial ring in $n$ variables over a field $K$. The edge ideal of $G$ is the ideal $I(G)$ of $R$ which is generated by those monomials $x_ix_j$ for…

Commutative Algebra · Mathematics 2020-08-13 Takayuki Hibi , Hiroju Kanno , Kyouko Kimura , Kazunori Matsuda , Adam Van Tuyl

We identify a family of $O(|E(G)|^2)$ nontrivial facets of the connected matching polytope of a graph $G$, that is, the convex hull of incidence vectors of matchings in $G$ whose covered vertices induce a connected subgraph. Accompanying…

Combinatorics · Mathematics 2023-10-24 Phillippe Samer

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$ labels that is preserved only by a trivial automorphism. In this paper we compute these…

Combinatorics · Mathematics 2016-07-27 Saeid Alikhani , Samaneh Soltani

The convex hull of the set of the incidence vectors of the matchings of a graph G is the matching polytope of the graph, M(G). The graph whose vertices and edges are the vertices and edges of M(G) is the skeleton of the matching polytope of…

Combinatorics · Mathematics 2017-04-04 Nair Abreu , Liliana Costa , Carlos Henrique do Nascimento , Laura Patuzzi

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$ labels that is preserved only by a trivial automorphism. The Kronecker product $G\times…

Combinatorics · Mathematics 2016-10-25 Saeid Alikhani , Samaneh Soltani

Let $G=(V,E)$ be a finite, simple, and connected graph. The locating-chromatic number of a graph $G$ can be defined as the cardinality of a minimum resolving partition of the vertex set $V(G)$ such that all vertices have different…

Combinatorics · Mathematics 2024-08-14 Dian Kastika Syofyan , Suhadi Wido Saputro , Edy Tri Baskoro , Ira Apni Purwasih

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$ labels that is preserved only by a trivial automorphism. The co-normal product $G\star…

Combinatorics · Mathematics 2017-07-21 Saeid Alikhani , Samaneh Soltani

A set $D$ of vertices is a strong dominating set in a graph $G$, if for every vertex $x\in V(G) \setminus D$ there is a vertex $y\in D$ with $xy\in E(G)$ and $deg(x) \leq deg(y)$. The strong domination number $\gamma_{st}(G)$ of $G$ is the…

Combinatorics · Mathematics 2023-06-05 Saeid Alikhani , Nima Ghanbari , Michael A. Henning

The general position number ${\rm gp}(G)$ of a graph $G$ is the cardinality of a largest set of vertices $S$ such that no element of $S$ lies on a geodesic between two other elements of $S$. The complementary prism $G\overline{G}$ of $G$ is…

Combinatorics · Mathematics 2020-01-08 Neethu P. K. , Ullas Chandran S. V. , Manoj Changat , Sandi Klavžar

The general sum-connectivity index of a graph $G$ is defined as $\chi_\alpha(G)=\sum\limits_{uv\in E(G)} {(d(u)+d(v))^{\alpha}}$, where $d(v)$ denotes the degree of the vertex $v$ in $G$ and $\alpha$ is a real number. In this paper it is…

Combinatorics · Mathematics 2018-07-13 M. K. Jamil , I. Tomescu

The automorphisms of a graph act naturally on its set of labeled imbeddings to produce its unlabeled imbeddings. The imbedding sum of a graph is a polynomial that contains useful information about a graph's labeled and unlabeled imbeddings.…

Combinatorics · Mathematics 2007-05-23 Robert G. Rieper

The F-index of a graph is defined as the sum of cubes of the vertex degrees of the graph. This was introduced in 1972, in the same paper where the first and second Zagreb indices were introduced to study the structure-dependency of total…

Combinatorics · Mathematics 2015-11-23 Nilanjan De , Sk. Md. Abu Nayeem , Anita Pal

The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$ labels that is preserved only by a trivial automorphism. The lexicographic product of…

Combinatorics · Mathematics 2016-06-28 Saeid Alikhani , Samaneh Soltani

Suppose a finite, unweighted, combinatorial graph $G = (V,E)$ is the union of several (degree-)regular graphs which are then additionally connected with a few additional edges. $G$ will then have only a small number of vertices $v \in V$…

Combinatorics · Mathematics 2023-10-25 Tony Zeng

The Szeged index of a graph is an invariant with several applications in chemistry. The power graph of a finite group $G$ is a graph having vertex set as $G$ in which two vertices $u$ and $v$ are adjacent if $v=u^m$ or $u=v^n$ for some…

Combinatorics · Mathematics 2025-10-30 Subarsha Banerjee

Let $G$ be a graph with $n$ vertices, and let $A(G)$ and $D(G)$ denote respectively the adjacency matrix and the degree matrix of $G$. Define $$ A_{\alpha}(G)=\alpha D(G)+(1-\alpha)A(G) $$ for any real $\alpha\in [0,1]$. The collection of…

Combinatorics · Mathematics 2017-09-05 Huiqiu Lin , Xiaogang Liu , Jie Xue